In general, groundwater sampling may be performed with a water pump or it may be performed by lowering a sampler to target depth within a single borehole. The groundwater sampling methods by pumping are divided into a volume-based purging and sampling and a low flow purging and sampling according to water pumping rate. In the former, there are indicated the problems, such as the disturbance of groundwater within a borehole according to a great amount of the groundwater being pumped, the contact of groundwater sample with air upon sampling, and the loss of volatile organic compounds. In the latter, the low flow purging and sampling method, it minimizes the disturbance of groundwater within a borehole according to the water pumping, and the amount of groundwater to be treated. However, it still has the problems, such as the change in water quality by the contact with air, and the loss of volatile organic compounds. In particular, the groundwater sampling by pumping is not suitable for profiling water quality with depth within a borehole.
Under the circumstances, it is required to develop an apparatus capable of simultaneously collecting groundwater samples for various analysis purposes at multiple depths, without having any limitations in the number of samplers to be deployed within a borehole. In addition, a sampler to be developed have to seal sample bottles under in-situ conditions, to prevent any change of the water quality by a contact with air and any loss of a volatiles, and to prevent secondary contamination during sample transfer process by making it possible for groundwater samples to be directly transferred to a laboratory, without being moved into another sample bottle.
Therefore, the present invention has been made to solve the aforementioned problems, and it is an object of the present invention to provide an apparatus and method for groundwater sampling, using hydraulic couplers, whereby the hydraulic couplers are each installed at both ends of a water sampling pipe and the sockets and plugs of couplers are separated to seal sampling pipe in-situ by air-cylinder. A number of samplers are deployed within a borehole but the groundwater samples are simultaneously taken at different targeted depths by the operation of the air-cylinders attached to each sampler.
In accordance with an aspect of the present invention, there is provided an apparatus for groundwater sampling, using hydraulic couplers, comprising: a water sampling pipe (30) with a top end connected to a second socket (21) in a single unit and a bottom end connected to a first plug (11) in a single unit; a center jacket pipe (50) receiving the water sampling pipe (30) so that the first plug (11) protrudes outside the bottom end; a first socket (12) attachably/detachably connected to the first plug (11); a second plug (22) attachably/detachably connected to the second socket (21) at an outside top end of the water sampling pipe (30); and a lift member (40) with one end connected to the second plug (22), to lift the water sampling pipe (30).
Further, the water sampling pipe (30) is connected to the second plug (22) at the top end and the first socket (12) at the bottom end, to open the both ends of the water sampling pipe (30), and thereafter, the water sampling pipe (30) is positioned at a targeted depth within a groundwater borehole, to permit a groundwater sample to flow into the water sampling pipe (30).
Further, when the water sampling pipe (30) is lifted by the lift member (40), socket covers (13) positioned at the outer circumferences of the first and second sockets (12, 21) are held by a bottom surface (α) of the center jacket pipe (50) and by a raised part (β) formed inside the center jacket pipe (50), respectively, whereby the first socket (12) is separated from the first plug (11) and the second socket (21) is separated from the second plug (22), and the both ends of the water sampling pipe (30) are sealed.
Further, the first socket (12) is disposed in a lower jacket pipe (51) connected to the bottom end of the center jacket pipe (50), so that the first socket (12) falls into the lower jacket pipe (51) when it is separated from the first plug (11), thereby preventing the first socket (12) from being lost.
Further, a plurality of groundwater samplers are continuously connected to each other/one another lengthwise by a connection unit (W) and are positioned at multiple depths, to simultaneously take groundwater samples by depths within the borehole.
In accordance with the other aspect of the present invention, there is provided a method for groundwater sampling, using a hydraulic coupler, comprising: a step (S100) of combining a groundwater sampler by connecting a second socket (21) positioned at a top end of a water sampling pipe (30) to a second plug (22) and connecting a first plug (11) positioned at a bottom end thereof to a first socket (12), so that the both ends of the water sampling pipe (30) are open; a step (S200) of deploying a plurality of the groundwater samplers to targeted depths within a groundwater borehole; a step (S300) of sealing the both ends of the water sampling pipe (30) by lifting the water sampling pipe (30), using a lift member (40), so that the coupler sockets at the both ends of the water sampling pipe (30) are separated from the plugs, respectively; and a step (S400) of securing a groundwater sample by separating the water sampling pipe (30) from the groundwater sampler after pulling up the groundwater sampler outside the borehole.
As described above, the apparatus for groundwater sampling using the hydraulic coupler in accordance with the present invention is installed at a target depth within the groundwater borehole in the state that the water sampling pipe to retain a groundwater sample is open. Thus, it has the effect of preventing the water sampling pipe from being deformed or broken by the water pressure which increases as the depth, is deeper.
Furthermore, in accordance with the present invention, the present invention has the effect of taking samples of a great amount of groundwater by using the single water sampling pipe.
Furthermore, in accordance with the present invention, after the groundwater samplers are connected to one another and deployed, groundwater samples can be simultaneously taken at multiple depths by the single operation of the lift member.
Furthermore, in accordance with the present invention, the groundwater samples are in-situ sealed at the depth where the samples are taken. Thus, the groundwater samples can be transferred to a laboratory, without any change in water quality by contact with air and any loss of a volatile organic compound.
Furthermore, in accordance with the present invention, the water sampling pipe is re-usable after it is decontaminated. Thus, it is cost-effective and environmentally friendly.
[Brief description of reference numbers of major elements]10: first coupler11: first plug12: first socket13: socket cover14: bottom inflow opening15: plug pin16: socket pin20: second coupler21: second socket22: second plug23: top inflow opening30: water sampling pipe40: lift member41: connection pipe42: groundwater inflow opening43: cylinder44: piston50: center jacket pipe50′, 51′, 52′, 53′: inflow openings51: lower jacket pipe52: upper jacket pipe53: uppermost jacket pipe60: connection ringC: connection unitH: boreholeL: connection lineP: pumpW: wireβ: raised part